Composite propeller shaft construction and method of making

ABSTRACT

A VEHICLE PROPELLER SHAFT INCLUDES A PAIR OF SPACED END MEMBERS HAVING INNER ENDS WITH CHARACTERIZED SURFACES. A LIGHT BUT STIFF CYLINDRICAL ARBOR, SUCH AS OF POLYURETHANE FOAM, CONNECTS THE END MEMBERS AND A TUBE FORMED OF HARDENED THERMOSETTING RESIN REINFORCED WITH FIBER GLASS FILAMENTS IF FORMED ON THE ARBOR AND INTERLOCKINGLY ENGAGES THE CHARACTERIZED SURFACES OF THE END MEMBERS. A METHOD OF FORMING SUCH A SHAFT INCLUDES STEPS OF FORMING A POLYURETHANE FOAM ARBOR BETWEEN THE END MEMBERS AND FORMING THE RESIN BONDED FIBER GLASS TUBE N PLACE OF THE ARBOR AND END MEMBERS.

.1971 c. w. WILLIAMS 3,553,978

comfosmn PROPELLER SHAFT CONSTRUCTION AND METHOD OF MAKING OriginalFiled June 7. 1967 INVENTOR ATTORNEY United States Patent 3,553,978COMPOSITE PROPELLER SHAFT CONSTRUCTION AND METHOD OF MAKING Charles W.Williams, Essexville, Mich., assignor to General Motors Corporation, acorporation of Delaware Original application June 7, 1967, Ser. No.644,184. Divided and this application Oct. 6, 1969, Ser. No. 871,091

Int. Cl. F16c 3/02 US. Cl. 64-1 4 Claims ABSTRACT OF THE DISCLOSURE Avehicle propeller shaft includes a pair of spaced end members havinginner ends with characterized surfaces. A light but stiff cylindricalarbor, such as of polyurethane foam, connects the end members and a tubeformed of hardened thermosetting resin reinforced with fiber glassfilaments is formed on the arbor and interlockingly engages thecharacterized surfaces of the end members. A method of forming such ashaft includes steps of forming a polyurethane foam arbor between theend members and forming the resin bonded fiber glass tube in place onthe arbor and end members.

This application is a division of application Ser. No. 644,184, filedJune 7, 1967.

This invention relates generally to propeller shafts for thetransmission of power and more particularly to the construction andmethod of making a novel propeller shaft adapted to be mounted betweenuniversal joints of a motor vehicle drive train.

Propeller shafts for motor vehicles have for many years been commonlyconstructed from a steel tubular member welded between the connectingyokes of universal joints or other suitable end members. In order toprovide sufficient stiffness in both torsion and bending, tubes ofsubstantial thickness and diameter have been required which have notonly added substantial weight to the vehicle but, addition, haverequired care in manufacture and proper balancing to avoid undesirablevibration problems.

It is, accordingly, an object of the present invention to provide animproved propeller shaft construction combining features of light weightand high critical vibration speed.

It is a further object of my invention to provide a method ofmanufacturing a propeller shaft having improved properties.

These and other objects of the invention will be more clearly understoodfrom the following description of a preferred embodiment of a propelleror drive shaft according to the invention and a method of forming samewherein:

FIG. 1 is a plan view of a drive shaft according to the inventionpartially broken away to show certain details of interior construction;

FIG. 2 is a view partially diagrammatic in nature and illustrating thesteps in the manufacture of the drive shaft of FIG. 1 comprising formingan arbor between the end members;

FIG. 3 is a fragmentary plan view illustrating the drive shaft of FIG. 1in a partial state of completion;

FIG. 3a is a view similar to FIG. 3 but showing an alternativeembodiment of the end member characterized surfaces;

FIG. 4 is a pictorial view illustrating the step in the manufacture ofthe drive shaft of FIG. 1 of applying the layers of glass fibers;

FIG. 5 is a plan view illustrating the step of applying uncured resin tothe fiber glass layers of the shaft; and

FIG. 6 is a plan view illustrating the step of curing the resin byheating.

Referring now to the drawings in more detail: FIG. 1 discloses apropeller shaft constructed according to the invention and generallyindicated by numeral 10. Propeller shaft 10 comprises a pair of spacedend members 12 having ears 14 which are adapted to act as yoke portionsof universal joints to which the end members are connectable for thereceiving and transmission of torque between members of a vehicle drivetrain. The end members include inner end portions 16 having outersurfaces 18 which are preferably characterized such as by knurling, asbest shown in FIG. 3, or scalloping, as best shown in FIG. 3a. Endmembers members 12 also include inwardly opening axially extendingrecesses 20 located interiorly of surfaces 18.

Recesses 20 receive the end portions of an arbor 22 formed of a lightweight relatively stiff material, such as, for example, polyurethanefoam. Arbor 22 extends between the end members and has, except for itsend portions, a diameter equal to that of surfaces 18.

Applied on the outer surfaces of arbor 22 and end member surfaces 18 isa torque tube 24 formed of a hardened thermosetting resin reinforcedwith fi-ber glass filaments. Tube 24 is preferably formed of a pluralityof layers of glass fibers including helically wound woven layersalternating with longitudinally extending fiber layers which give thetube torsional strength and bending strength respectively. The glassfiber layers may be applied by known methods to obtain the desireddegree of torsional and bending strength in accord with the size andweight of shaft desired. The glass fiber layers are impregnated withknown thermosetting resins of suitable strength, for example, epoxyresin which is hardened by heating to curing temperature.

Referring to FIGS. 2-6, the steps of one method of forming a propellershaft of the type shown in FIG. 1 are illustrated. In FIG. 2, a pair ofend members 12 have been placed in spaced axial relationship and acylindrical mold. such as split aluminum tube 25, is clamped about outersurfaces 18 so as to connect members 12 and form a cylindrical cavity 26therebetween. A known foamable urethane formulation is then added to thecavity where it is foamed and cured to a rigid low density polyurethanefoam within cavity 26 and recesses 20 of members 12 to form a light butstiff cylindrical arbor 22 connecting the members as shown in FIG. 3.

Next, alternate layers of longitudinally extending and helically wovenglass fibers are applied to the outer surface or arbor 22 and surfaces18 of end members 12. Any suitable means of making such application maybe utilized, one such means being disclosed in FIG. 4. In this method,the end member and arbor assembly is moved upwardly through a tubularmember 27 which includes apertures 28 through which glass fibers are fedto produce a layer of longitudinally oriented glass fibers along theouter surface of the arbor and end members. Surrounding tube 27 is atable 30 on which clockwise and counterclockwise moving spools 32 and 34are respectively moved in undulating paths in a known manner to form abraided layer of fiber glass filaments on the propeller shaft over thelongitudinal layer previously applied. This process may be repeated anydesired number of times to obtain the desired number of layers oflongitudinal and braided fiber glass filaments.

Following the application of the fiber glass layers, they areimpregnated with a suitable thermosetting resin, such as epoxy, as isindicated by FIG. 5. The shaft 10 may be rotated during application ofthe resin. If desired, this step may be alternated with the previouswrapping step to provide for impregnating of a layer or group of fiberglass layers after each is applied. Suitable dispensing layer or layersof fiber glass filaments.

By the use of proper equipment it is also possible to apply the resin tothe fiberglass filament before the wrapping step takes place so that,upon wrapping the filament in the desired pattern on the propeller shaftarbor and end members, the interstices are at once filled with uncuredresin with the excess being squeezed out by the wrapping process.

Following the wrapping and impregnating steps the shaft assembly ispassed through a heater 38 in Which the thermosetting resin is cured andhardened. In order to avoid deformation of the shaft in the curingprocess, it may be rotated while being moved through the curing oven.Alternatively, if desired, the shaft may be hung vertically during thecuring process so that no bending moments are applied to the shaftlength while it is being cured.

From the wrapping, impregnating and curing processes, the depressions inthe characterized surfaces 18 of the end members are filled withportions of fiber glass filaments and hardened resin. This forms astrong interlocking engagement between the tube 24 and end members 12 sothat the transmission of torque loads therethrough will not easily breakthe bonds between them. The helically wound fiber glass strands transmittorque loading passing through the shaft between the end members, whilethe longitudinally extending strands absorb bending loads and hold theshaft relatively straight in its applied position. The main purpose ofthe arbor 22 is its use in the manufacture of the shaft in obtaining astraight tube joining the end members; however, it remains in placeafter assembly and serves to stiffen the tube slightly without addingundue weight to the assembly.

By the above method, a drive shaft is constructed in which the lightweight of the tube as well as the high strength and low elasticity ofthe glass filaments results in a propeller shaft having a high degree ofstrength in proportion to its weight as well as a high critical speed ofvibration. This makes the shaft useful in high speed drive lineapplications and reduces the balancing problems in such applications. Anadditional advantage is that the resin bonded fiber glass tube is notsubject to oxidation attacks as are steel tubes and thus may beespecially useful in applications where corrosive conditions exist.

The method of forming the fiber glass tube in place on the arbor andcharacterized surfaces of the end members is also advantageous in that amuch better and stronger bond is formed between the tube and the endmembers than can be accomplished where the tube is formed on a separateremovable arbor and afterward bonded to the end members to form apropeller shaft. The use of polyurethanefoam as an arbor makes arelatively inexpensive and light weight construction; however, it iswithin the scope of my invention to utilize as an arbor any othersuitably stiff, light weight and inexpensive material as an arbor onwhich to form the fiber glass tube.

While my invention has been described by the use of a particularembodiment and method chosen for purposes of illustration, numerouschanges may be made by those skilled in the art within the scope of theinventive concept disclosed and it is, accordingly, desired that theinvention not be limited except by the language of the following claims.

I claim:

1. A composite propeller shaft comprising a pair of spaced torquetransmitting end members connectable with driving and driven meansrespectively,

a light but relatively stiff cylindrical arbor connecting said endmembers and a fibrous resin bonded tube formed around said arbor andextending around portions of said end members, said tube being securedto said end members to transmit torque therebetween.

2. A composite propeller shaft comprising a pair of spaced torquetransmitting end members connectable with driving and driven meansrespectively, said end members including axially aligned generallycylindrical inner end portions having characterized surfaces a light butrelatively stiff cylindrical arbor axially aligned with and connectingsaid inner end portions and a resin bonded fiber glass tube formed inplace on said arbor and said end portions, said tube interlockinglyengaging the characterized surfaces of said end portions to form astrong connection for the transmission of torque between said endmembers through saidrtube.

3. The combination of claim 2 wherein said tube includes both helicallyand longitudinally oriented fiber glass filaments to provide strength intorsion and bending modes respectively.

4. The combination of claim 3 wherein said arbor is formed of apolyurethane foam material.

References Cited UNITED STATES PATENTS 3,043,120 7/1962 Waldron 642 FREDC. MATTERN, JR., Primary Examiner R. HEALD, Assistant Examiner

